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PubMed1994

Intergeneric transfer and recombination of the 6-phosphogluconate dehydrogenase gene (gnd) in enteric bacteria.

The gnd gene, encoding 6-phosphogluconate dehydrogenase (EC 1.1.1.44), was sequenced in 87 strains of 15 species assigned to five nominal genera of the Enterobacteriaceae, including 36 isolates of Salmonella enterica and 32 strains of Escherichia coli. In S. enterica, the effective (realized) rate of recombination of horizontally transferred gnd sequences is only moderately higher than the rates for other chromosomal housekeeping genes. In contrast, recombination at gnd has occurred with such high frequency in Escherichia coli that the indicated evolutionary relationships among strains are not congruent with those estimated by sequence analysis of other genes and by multilocus enzyme electrophoresis. E. coli and S. enterica apparently have not exchanged gnd sequences, but those of several strains of E. coli have been imported from species of Citrobacter and Klebsiella. The relatively frequent exchange of gnd within and among taxonomic groups of the Enterobacteriaceae, compared with other housekeeping genes, apparently results from its close linkage with genes that are subject to diversifying selection, including those of the rfb region determining the structure of the O antigen polysaccharide.

Biological Evolution↗
PubMed1977

Intergeneric transfer of genes involved in the Rhizobium-legume symbiosis.

Genes that seem to be involved in the initial steps of infection of a legume by Rhizobium have been transferred, by transformation, to mutant strains of Azotobacter vinelandii that are unable to fix nitrogen. These genes code for a surface antigen that binds specifically to a protein from the host plant.

Antigens, Bacterial↗
PubMed1998

Intergeneric transfer of conjugative and mobilizable plasmids harbored by Escherichia coli in the gut of the soil microarthropod Folsomia candida (Collembola).

The gut of the soil microarthropod Folsomia candida provides a habitat for a high density of bacterial cells (T. Thimm, A. Hoffmann, H. Borkott, J. C. Munch, and C. C. Tebbe, Appl. Environ. Microbiol. 64:2660-2669, 1998). We investigated whether these gut bacteria act as recipients for plasmids from Escherichia coli. Filter mating with E. coli donor cells and collected feces of F. candida revealed that the broad-host-range conjugative plasmid pRP4-luc (pRP4 with a luciferase marker gene) transferred to fecal bacteria at estimated frequencies of 5.4 x 10(-1) transconjugants per donor. The mobilizable plasmid pSUP104-luc was transferred from the IncQ mobilizing strain E. coli S17-1 and less efficiently from the IncF1 mobilizing strain NM522 but not from the nonmobilizing strain HB101. When S17-1 donor strains were fed to F. candida, transconjugants of pRP4-luc and pSUP104-luc were isolated from feces. Additionally, the narrow-host-range plasmid pSUP202-luc was transferred to indigenous bacteria, which, however, could not maintain this plasmid. Inhibition experiments with nalidixic acid indicated that pRP4-luc plasmid transfer took place in the gut rather than in the feces. A remarkable diversity of transconjugants was isolated in this study: from a total of 264 transconjugants, 15 strains belonging to the alpha, beta, or gamma subclass of the class Proteobacteria were identified by DNA sequencing of the PCR-amplified 16S rRNA genes and substrate utilization assays (Biolog). Except for Alcaligenes faecalis, which was identified by the Biolog assay, none of the isolates was identical to reference strains from data banks. This study indicates the importance of the microarthropod gut for enhanced conjugative gene transfer in soil microbial communities.

Animals↗
PubMed1994

Integration and excision of a 2,4-dichlorophenoxyacetic acid-degradative plasmid in Alcaligenes paradoxus and evidence of its natural intergeneric transfer.

A self-transmissible 2,4-dichlorophenoxyacetic acid (2,4-D)-degradative plasmid, pKA2, has been identified in a new 2,4-D-degrading strain, Alcaligenes paradoxus 2811P, isolated from agricultural soil. pKA2 occurred as a 42.9-kb plasmid in strain 2811P. A derivative strain, 2811C, was isolated from a stock culture in which the entire pKA2 plasmid was apparently integrated into the host chromosome without loss of the 2,4-D+ phenotype. This interpretation is based on the disappearance of a free plasmid DNA band, a shift in the tfdA-hybridizing band to the chromosome, loss of transmissibility of the 2,4-D+ trait, and appropriate shifts in Southern hybridization bands of plasmid DNA compared with whole-cell DNA. The integrated plasmid of strain 2811C was excised either precisely or imprecisely after continued transfer on 2,4-D-containing medium. This suggests that a chromosome-free plasmid cycle may occur to optimize fitness under conditions of specific resource fluctuation. Another new 2,4-D-degrading strain, Pseudomonas pickettii 712, which was isolated from the same field plot but at a different time, was found to carry a plasmid that is nearly identical to pKA2. The plasmid of this strain, pKA4, is 40.9 kb long and has features in common with pKA2, such as high self-transmissibility, hybridization only to the tfdA gene among the 2,4-D-metabolic genes of 2,4-D-degradative plasmid pJP4, and similar restriction endonuclease-generated fragments. Furthermore, the genetic homology between the two plasmids was high since all fragments of pKA2 hybridized to pKA4. These results suggest that these two plasmids are closely related and thus their occurrence in two genera in nature is the result of natural horizontal gene transfer.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Intergenerational transfers: aging parents living with adult children and vice versa.

The family remains important for care of the elderly; less well understood is the significance of even aging parents for their offspring, which may be more so today than in the past and more so in the welfare states--with 'resourceful' old people--than in the less affluent societies. This study tries to verify this by an analysis of coresidence patterns between generations, with particular emphasis on the younger one. In particular, men with various handicaps may more often find refuge with their family of origin than do others, and more often today than they did in the not-so-distant past.

Adult↗
PubMed1983

Plasmid transfer in Pediococcus spp.: intergeneric and intrageneric transfer of pIP501.

Transfer of the broad-host-range resistance plasmid pIP501 from Streptococcus faecalis to Pediococcus pentosaceus and Pediococcus acidilactici occurred between cells immobilized on nitrocellulose filters in the presence of DNase. Expression of the pIP501-linked erythromycin and chloramphenicol resistance determinants was observed in transconjugants. Intrageneric transfer of pIP501 from a P. pentosaceus donor to various pediococcal recipients occurred at frequencies of 10(-4) to 10(-7) transconjugants per input donor cell. Intergeneric transfer of plasmid pIP501 from P. pentosaceus to S. faecalis, Streptococcus sanguis (Challis), and Streptococcus lactis was observed. Similar mating experiments showed no evidence for the transfer of the broad-host-range R-plasmid pAM beta 1 to Pediococcus spp. recipients.

Anti-Bacterial Agents↗
PubMed2003

Blastocyst development after intergeneric nuclear transfer of mountain bongo antelope somatic cells into bovine oocytes.

Intergeneric embryos were constructed by nuclear transfer using Mountain Bongo antelope somatic cells fused with enucleated bovine oocytes and their subsequent development in vitro was investigated. After two to six passages, starved or non-starved skin fibroblast cells were used as donor nuclei. In vitro matured bovine oocytes were enucleated by squeezing the first polar body and surrounding cytoplasm through a slit in the zona pellucida. After injection of a somatic cell into the perivitelline space, couplets were fused electrically and activated chemically, then subjected to different embryo culture treatments. Serum starvation had no effect on the frequency of cleavage to two cells or on development to the blastocyst stage in either sequential hamster embryo culture medium (HECM)-6/TCM-199 + serum or HECM-9/TC-199 + serum, or modified synthetic oviduct fluid (mSOF) culture medium. When couplets from non-starved donor nuclei were cultured, the frequency of cleavage (66 +/- 8% vs. 44 +/- 5%), development to >/=9 cells (46 +/- 6% vs. 24 +/- 4%), and formation of blastocysts (24 +/- 5% vs. 11 +/- 2%) were all significantly higher (p < 0.05) in the HECM-6 medium than in mSOF medium. In conclusion, bovine oocytes can support blastocyst development after intergeneric fusion with bongo fibroblasts. This technique could potentially be used as an alternative to using scarce bongo oocytes in attempts to propagate these endangered animals.

Animals↗
PubMed2006

Production of blastocysts after intergeneric nuclear transfer of goral (Naemorhedus goral) somatic cells into bovine oocytes.

Interspecies cloning may be a useful method to help conserve endangered species and to study nuclear-cytoplasm interaction. The present study investigated in vitro development of goral (Naemorhedus goral) intergeneric nuclear transfer embryos produced by fusing goral fibroblasts with enucleated metaphase II (MII) bovine oocytes. After two to five passages, serum-starved or non-starved goral skin fibroblast cells were transferred into enucleated MII bovine oocytes. Couplets were electrically fused and chemically activated, and then cultured in either modified synthetic oviduct fluid (mSOF) or tissue culture medium-199 (TCM-199) supplemented with 10% FBS. Serum starvation of donor cells did not affect the fusion rate and or development to of cells to the two-cell stage, to more than 9-cells, or to morulae, regardless of culture medium. Three blastocysts from 202 fused embryos were obtained when embryos reconstructed with non- serum- starved donor cells were cultured in mSOF. However, no blastocysts were obtained when the embryos reconstructed with serum-starved donor cells were cultured in mSOF. The total cell number of goral intergeneric embryos averaged 130.3 (range 105-180). In conclusion, this study demonstrated that bovine oocytes can support blastocyst development after intergeneric SCNT with goral fibroblasts.

Animals↗
PubMed1997

High efficiency intergeneric conjugal transfer of plasmid DNA from Escherichia coli to methyl DNA-restricting streptomycetes.

Many streptomycetes, including S. coelicolor A3(2), possess a potent methyl-specific restriction which can present an effective barrier to the introduction of heterologous DNA. We have compared the efficiency of intergeneric conjugal transfer of different types of plasmids to S. coelicolor and S. lividans 66 using two E. coli donors: the standard, methylation proficient strain S17-1, and the methylation deficient donor, ET12567(pUB307). We demonstrate that the methylation deficient donor can yield > 10(4)-fold more S. coelicolor exconjugants than the standard donor. In the case of pSET152 derivatives, which integrate into the host chromosome by site-specific recombination, up to 10% of streptomycete spores in the conjugation mixture inherit the plasmid. The conjugation procedure is efficient enough to obtain exconjugants with 'suicide' delivery plasmids and therefore provides a simple route for conducting gene disruptions in methyl DNA-restricting streptomycetes, and possibly other bacteria.

Conjugation, Genetic↗
PubMed1981

Introduction of bacteriophage Mu into bacteria of various genera and intergeneric gene transfer by RP4::Mu.

The host range of coliphage Mu was greatly expanded to various genera of gram-negative bacteria by using the hybrid plasmic RP4::Mu cts, which is temperature sensitive and which confers resistance to ampicillin, kanamycin, and tetracycline. These drug resistance genes were transferred from Escherichia coli to members of the general Klebsiella, Enterobacter, Citrobacter, Salmonella, Proteus, Erwinia, Serratia, Alcaligenes, Agrobacterium, Rhizobium, Pseudomonas, Acetobacter, and Bacillus. Mu phage was produced by thermal induction from the lysogens of all these drug-resistant bacteria except Bacillus. Mu phage and RP4 or the RP4::Mu plasmid were used to create intergeneric recombinant strains by transfer of some genes, including the arylsulfatase gene, between Klebsiella aerogenes and E. coli. Thus, genetic analysis and intergeneric gene transfer are possible in these RP4::Mu-sensitive bacteria.

Anti-Bacterial Agents↗
PubMed1981

The conservation of DNA sequences over very long periods of evolutionary time. Evidence against intergeneric chromosomal transfer as an explanation for the presence of Escherichia coli tuf gene sequences in taxonomically-unrelated prokaryotes.

In the present study we tried to determine whether the presence of DNA sequences homologous to the Escherichia coli tuf gene (encodes peptide chain elongation factor Tu) in many taxonomically-unrelated prokaryotes is due to selective pressure for these sequences or due to the transfer of chromosomal material subsequent to the divergence of the genera from their progenitors. We found that the degree of sequence homology to the DNA immediately adjacent to the E. coli tuf A gene is either nonexistent or much less than that found for the tuf gene. Furthermore, the tuf-homologous sequences present in one prokaryote were found to be in large part the same as or a subset of those present in others. That is, various prokaryotes share a common subset of tuf-homologous sequences. These findings suggest that strong selective pressure and not recent intergeneric chromosomal transfer is responsible for the ubiquitous presence of certain tuf-homologous sequences. Because the genetic code is degenerate, DNA sequence need not be conserved to conserve protein sequence. Therefore, if the only function of these sequences is to encode protein, their persistence must mean that in some instances codon sequence is selected for.

Bacteria↗
PubMed2003

Rethinking the evolutionary theory of aging: transfers, not births, shape senescence in social species.

The classic evolutionary theory of aging explains why mortality rises with age: as individuals grow older, less lifetime fertility remains, so continued survival contributes less to reproductive fitness. However, successful reproduction often involves intergenerational transfers as well as fertility. In the formal theory offered here, age-specific selective pressure on mortality depends on a weighted average of remaining fertility (the classic effect) and remaining intergenerational transfers to be made to others. For species at the optimal quantity-investment tradeoff for offspring, only the transfer effect shapes mortality, explaining postreproductive survival and why juvenile mortality declines with age. It also explains the evolution of lower fertility, longer life, and increased investments in offspring.

Adaptation, Physiological↗
PubMed1993

Intergeneric conjugal transfer of Escherichia coli/Methylobacterium sp. shuttle vector.

To develop a host-vector system for Methylobacterium sp. using a construct based on a small indigenous methylotrophic plasmid, the E. coli--Methylobacterium sp. shuttle vector pWUBR (12.7 kb, Apr, Tcr) was constructed by joining the E. coli plasmid pBR328 and the cryptic plasmid pWU7 (7.8 kb), isolated from the soil facultative methylotrophic bacterium, Methylobacterium sp. strain M17. Via mobilization by the pDPT51 R plasmid, belonging to the IncP-1 incompatibility group, plasmid pWUBR was transferred into the original host of cryptic plasmid pWU7, strain M17, where a competition between the introduced hybrid plasmid and the indigenous cryptic plasmid took place, and into the plasmidless Methylobacterium sp. strain R2b. The stability of pWUBR in Tcr methylotrophic transconjugants after 25 generations of growth under nonselective conditions was more than 90% in both hosts. The ability to replicate in R2b strain demonstrates that the host spectrum of pWUBR is not restricted to the original host of pWU7 and indicates the possibility to use the present system for other methylotrophs.

Cloning, Molecular↗
PubMed2004

Intergeneric conjugal transfer of plasmid DNA from Escherichia coli to Kitasatospora setae, a bafilomycin B1 producer.

An effective transformation procedure for Kitasatospora setae was established based on transconjugation from Escherichia coli ET12567 (pUZ8002) using a phi C31-derived integration vector, pSET152, containing oriT and attP fragments. While no transconjugation was observed under the standard transconjugation conditions for Streptomyces species, sufficient transconjugation (>1 x 10(-6)) was achieved on ISP4 medium containing 30 mM MgCl(2) using a 25- to 125-fold excess of E. coli donor cells. In addition, the sequence and location of the chromosomal integration site attB of K. setae was identified for the first time in genera of non- Streptomyces actinomycetes. K. setae contains a single phi C31 attB site. Similar to the case of Streptomyces species, the attB site of K. setae is present within an ORF encoding a pirin-homolog, but the K. setae-attB sequence deviates slightly from the consensus sequence of Streptomyces attB sequences.

Actinobacteria↗
PubMed1993

Protoplast fusion: a tool for intergeneric gene transfer in bacteria.

Protoplasts can be isolated from bacterial cells by digestion of the cell wall with the help of lysozyme in presence of osmotic stabilizers. Fusion of protoplasts can be induced by chemical fusogens like polyethylene glycol. The electrofusion technique has been reported in bacteria in which the fusion frequency is much higher than that obtained by PEG induced protoplast fusion. This technology allows recombination to take place not only between related species but also between unrelated genera and is of great potential in the breeding and improvement of industrial strains. This review includes the information and developments on the protoplast fusion in bacteria with special reference to genetic recombination by protoplast fusion between phylogenetically unrelated bacteria.

Journal Article↗
PubMed2002

Construction and intergeneric conjugative transfer of a pSG5-based cosmid vector from Escherichia coli to the polyisoprene rubber degrading strain Micromonospora aurantiaca W2b.

A non-rubber degrading mutant of the polyisoprene rubber degrading bacterium Micromonospora aurantiaca W2b lacking the capability to form halos on latex overlay agar plates was isolated after N-methyl-N-nitro-N-nitrosoguanidine mutagenesis. A 10.3-kb shuttle cosmid vector pGM446 was constructed from the Streptomyces cloning vectors pGM160 and pOJ446. This vector was transferred by conjugation from Escherichia coli to M. aurantiaca W2b. The frequency of formation of exconjugants with pGM446 was 3.6 x 10(-3). This vector could be useful for shotgun cloning of genes into the non-rubber degrading mutant L1 from M. aurantiaca W2b.

Butadienes↗